1. Field of the Invention
This invention relates to improvements in current multiplying and dividing circuits, and more particularly to improvements in current multiplying and dividing circuits that enable current multiplication by values that are not restricted to integer values.
2. Relevant Background
Presently, circuits for performing current multiplication or division are restricted to performing integer multiplications or divisions. An example of such circuit is shown in FIG. 1, in which a circuit 10 uses a current mirror arrangement to produce an output current Iout on node 11 that is n times the input current Iin. The current mirror circuit has an input current path through two NPN transistors 13 and 14 connected in series with the input current source 15 and a resistor 16 between a V.sub.cc rail 20 and ground. An output current path is provided by NPN transistors 23 and 24 in series with a resistor 25, connected between the output terminal 11 and ground 21. The emitters of the NPN transistors 23 and 24 in the output current flow path are n-times the size of the emitters of the respective NPN transistors 13 and 14 in the input current flow path, and, the resistor 16 is n-times the size of the resistor 25 in the output current flow path. Accordingly, the current that flows in the current path through the NPN transistors 23 and 24 and the resistor 25 mirrors the current that flows in the NPN transistors 13 and 14 and the resistor 16, multiplied by the value of n.
The circuit 10 also has a PNP transistor 28 connected in a current flow path with a first current source 29 between the V.sub.cc rail 20 and ground 21. Also, a N-channel MOS transistor 32 is connected in a current flow path with a second current source 33 between the V.sub.cc rail 20 and ground 21. The bases of the NPN transistors 14 and 24 and the base of the PNP transistor 28 are connected together and to the source of the NMOS transistor 32 and the second current source 33. Similarly, the bases of the NPN transistors 13 and 23 are connected together and to the emitter of the the PNP transistor 28.